Pep Guardiola, right, was one of the contenders to succeed Sir Alex Ferguson at United (Picture: AFP/Getty Images)

The topic of who was going to replace Sir Alex Ferguson when he eventually retired has debated for some time.

When the legendary manager was set to retire in 2002, Sven Goran Eriksson was the man set to get the job.

The former England manager revealed in his autobiography that he had got as far as signing at contract with United.

I had a contract with England until the 2006 World Cup and I would be severely criticised if I broke that contract. But this was an opportunity to manage Manchester United. A contract was signed – I was United’s new manager.

United fans will be relieved that the deal fell through and as time went by, with former players Roy Keane, Mark Hughes and Steve Bruce all being linked to the position, before failing to show they had the credentials, Jose Mourinho was tipped as the favourite.

In 2011, Sir Bobby Charlton revealed he would not want Mourinho at the club though, thanks to failure to bring through youth players.

I don’t see him here. He’s got a talent but maybe if he ever came here the philosophy of youth football might never be the same again.

After Mourinho, then Real Madrid boss, stuck his thumb in Tito Vilanova’s eye on the touchline during a game against Barcelona, Charlton again reiterated his belief that the Chelsea man was not cut out for the United job.

A United manager wouldn’t do that. Mourinho is a really good coach but that’s as far as I would go really.

Bearing that in mind, whilst it was astonishing that United opted to appoint the unproven David Moyes when Ferguson retired, it shouldn’t have come as a surprise that Mourinho was not offered the job.

Respected Spanish journalist Diego Torres, who writes for El País, brought out a book last year revealing Mourinho’s reaction to the snub.

Mourinho thought that Ferguson was, besides his ally, also his friend and godfather. He was convinced that they were tied by a relationship of genuine trust. He thought that his fabulous collection of titles constituted an ‘endorsement’ unreachable to any other contenders. When he knew that Ferguson had chosen Moyes he was struck by a terrible disbelief. Mourinho wouldn’t stop calling them [his agency]. His ‘interlocutors’ had heard him sob loudly and they were spreading the word. The most feared man in the company was crushed.

Whilst United fans are now happy with the appointment of Louis van Gaal, whose belief in youth has shown him to be the ideal manager, they have learnt this week that Pep Guardiola might have been the man in the dugout instead.

In Pep Confidential: The Inside Story of Pep Guardiola’s First Season at Bayern Munich, a book written by the former Barcelona manager’s close friend and journalist Marti Perarnau, he reveals his admiration for United.

The day after beating Real Madrid in the Champions League semi-final, Guardiola and Estiarte travelled to Manchester to watch their next opponents in action. It was 4 May 2011, and the pair sat together in the stands of Old Trafford watching Sir Alex Ferguson’s team beat Schalke 4-1. Once again Pep had turned to his friend and said: ‘I like this atmosphere. I could see myself coaching here one day.’ Guardiola has always felt a deep admiration, almost veneration, for the legendary teams and players of Europe.

Given the choice between Guardiola and Van Gaal, who would United fans choose? Or should the Bayern Munich manager’s appointment be something supporters should look forward to after Van Gaal’s retirement?